This invention relates to a self-operated regulating valve, and a compression refrigerating machine having it.
FIG. 9 is a system diagram showing a multistage compression turbo-refrigerating machine according to prior art. As shown in the drawing, in an evaporator 1, a refrigerant liquid (e.g., an organic refrigerant such as a fluorocarbon) is heated with cold water (or brine) 3, flowing in a tube 2, to generate a refrigerant gas. At this time, the cold water 3 is cooled by heat exchange in the evaporator 1, and then delivered to the outside.
A turbo-compressor 4 having two impellers takes in the refrigerant gas evaporated by the evaporator 1, compresses it at two stages by the two impellers rotated by an electric motor (not shown), and discharges a high temperature, high pressure refrigerant gas. A refrigerant gas from an inter-cooler 5 is also taken into the impeller located at the second stage (intermediate stage). In a condenser 6, the high temperature, high pressure refrigerant gas discharged from the turbo-compressor 4 is cooled with cooling water 8, flowing in a tube 7, to condensate and liquefy it. At this time, the cooling water 8 is heated by heat exchange in the condenser 6, and then discharged to the outside. A refrigerant liquid formed by condensation is accumulated at the bottom of the condenser 6.
The inter-cooler 5 evaporates part of a refrigerant supplied from the condenser 6, and allows the resulting refrigerant gas to be taken into the second stage of the turbo-compressor 4 via a pipe line 10. Then, the refrigerant gas is compressed by the second-stage impeller to increase latent heat. That is, in the inter-cooler 5, the refrigerant liquid fed from the condenser 6 is reduced in pressure by a first-stage orifice to an intermediate pressure to expand it, converting it into a refrigerant gas partly. This refrigerant gas, as stated above, is taken into (intermediately sucked into) the second-stage impeller of the turbo-compressor 4. On the other hand, the remaining refrigerant liquid cooled upon evaporation of the refrigerant liquid is further reduced in pressure by a second-stage orifice, and then fed into the evaporator 1. Simultaneously, the inter-cooler 5 has the function of retaining a constant pressure difference between the condenser 6 and the evaporator 1. For this purpose, an intermediate suction valve 9 is put into the pipe line 10 to regulate the flow rate of the refrigerant gas supplied into the turbo-compressor 4 via the pipe line 10. Concretely, the internal pressure P1 of the condenser 6 and the internal pressure P2 of the evaporator 1 are detected, and a pressure switch is activated on condition that a differential pressure, xcex94P, between the two pressures exceeds a set value. Upon activation of the pressure switch, an electromagnetic valve or an electric valve is opened. Whereas the valve is closed when the differential pressure is not more than the set value. That is, the above-described intermediate suction valve 9 according to the prior art is constituted as a valve comprising the pressure switch and the electromagnetic or electric valve integrated.
With the turbo-refrigerating machine according to the prior art, a valve comprising a pressure switch and an electromagnetic or electric valve integrated is used as the intermediate suction valve 9 for maintaining the pressure difference between the internal pressure of the evaporator 1 and the internal pressure of the condenser 6 at a constant value. Thus, the intermediate suction valve 9 itself is large in size and expensive. The cost of the turbo-refrigerating machine is boosted accordingly.
With the turbo-refrigerating machine, moreover, there are generally other cases, in addition to the above-mentioned case, in which the flow rate of a fluid, such as a refrigerant, needs to be adjusted in accordance with the differential pressure between one of the pressures, P1, and the other pressure, P2, i.e., xcex94P (=P1xe2x88x92P2).
The present invention has been accomplished in light of the above-described prior art, and its object is to provide a self-operated regulating valve, and a compression refrigerating machine having it, which are capable of autonomously opening or closing a valve for flowing a fluid, such as a refrigerant, with the use of a low cost, simple configuration in accordance with a differential pressure between a pressure at one site and a pressure at another site.
A first invention for attaining the above object is a self-operated regulating valve characterized in that one pressure introduced into one pressure transmission chamber, which is a space formed between a cylindrical valve body and one end surface of a spool formed axially movably in an internal space of the valve body, acts on the one end surface of the spool; other pressure introduced into other pressure transmission chamber, which is a space formed between the valve body and the other end surface of the spool, and a spring force of a preload spring acts on the other end surface of the spool; and a through-hole is provided in the spool, whereby when a difference between the one pressure and the other pressure exceeds a set value, the through-hole and pipe lines connected to the valve body communicate to bring the self-operated regulating valve into an open state, while when the difference does not exceed the set value, the through-hole and the pipe lines are cut off to bring the self-operated regulating valve into a closed state.
According to this invention, the valve can be opened or closed according to the differential pressure between the one pressure and the other pressure. Consequently, a simple-structured inexpensive valve can be supplied.
A second invention is a self-operated regulating valve characterized in that one pressure introduced into one pressure transmission chamber, which is a space formed between a cylindrical valve body and a flange portion provided midway through a spool, acts on the flange portion of the spool; other pressure introduced into other pressure transmission chamber, which is a space formed between the valve body and one end surface of the spool formed axially movably in an internal space of the valve body, acts on the one end surface of the spool; and the spool moves according to a differential pressure between the one pressure and the other pressure, whereby the other end surface of the spool closes or opens a region between opening ends of two pipe lines connected to the valve body.
According to this invention, like the first invention, the valve can be automatically opened or closed according to the differential pressure between the one pressure and the other pressure. At this time, the region between the opening ends of the two pipe lines connected to the valve body is closed or opened by the other end surface of the spool in accordance with the movement of the spool. Thus, sealability at this site can be maintained more satisfactorily. Consequently, a simple-structured inexpensive valve can be supplied, with sealability of the opening/closing portion being further improved.
A third invention is a self-operated regulating valve characterized in that a pressure of a fluid controlled by the self-operated regulating valve acts, as one pressure, on one end surface of a spool formed axially movably in an internal space of a cylindrical valve body; other pressure introduced into a pressure transmission chamber, which is a space formed between the valve body and the other end surface of the spool, and a spring force of a preload spring acts on the other end surface of the spool; and a through-hole is provided in the spool, whereby when a difference between the one pressure and the other pressure exceeds a set value, the through-hole and pipe lines connected to the valve body communicate to bring the self-operated regulating valve into an open state, while when the difference does not exceed the set value, the through-hole and the pipe lines are cut off to bring the self-operated regulating valve into a closed state.
According to this invention, the valve can be automatically opened or closed according to the differential pressure between the one pressure, the pressure of the fluid to be controlled, and the other pressure. Consequently, there can be supplied a valve of a simpler structure and at a lower price than the self-operated regulating valve described as the first invention.
A fourth invention is a multistage compression refrigerating machine having an inter-cooler, characterized in that the self-operated regulating valve described in the first invention or second invention is interposed midway through a pipe line for returning a refrigerant from the inter-cooler to a compressor; an internal pressure of a condenser is exerted as one pressure on the self-operated regulating valve, and an internal pressure of an evaporator is exerted as other pressure on the self-operated regulating valve, whereby when a differential pressure between the two pressures exceeds a set value, the self-operated regulating valve is brought into an open state.
According to this invention, the pressure of the inter-cooler can be adjusted to an appropriate value autonomously by a valve of a simple structure and at a low price.
A fifth invention is a compression refrigerating machine having a compressor configured such that a bulkhead separates a casing housing a drive motor of the compressor from a casing housing a speed increasing gear and impellers, sealing means is provided in a gap between a rotating shaft piercing through the bulkhead and the bulkhead so that a lubricating oil having lubricated the speed increasing gear does not enter the casing for the drive motor, a refrigerant gas is introduced into the casing for the drive motor to cool respective portions of the drive motor, and the refrigerant gas is then discharged from the casing, and characterized in that
the self-operated regulating valve described in any one of the first to third inventions is interposed midway through a pipe line for discharging a cooling refrigerant from the casing for the drive motor, an internal pressure of the casing for the drive motor is exerted as one pressure on the self-operated regulating valve, and an internal pressure of the casing for the speed increasing gear is exerted as other pressure on the self-operated regulating valve, whereby when a differential pressure between the two pressures exceeds a set value, the self-operated regulating valve is brought into an open state.
According to this invention, the internal pressure of the casing for the drive motor can be adjusted autonomously to an appropriate value by a valve of a simple structure and at a low price, whereby entry of the lubricating oil from a gear chamber can be prevented.
A sixth invention is a compression refrigerating machine having a compressor configured such that a refrigerant gas is introduced into a casing of a drive motor of the compressor to cool respective portions of the drive motor, and then the refrigerant gas is discharged from the casing, and characterized in that
the self-operated regulating valve described in any one of the first to third inventions is interposed midway through a pressure equalizing pipe line for equalizing a pressure on a refrigerant supply port side, where a cooling refrigerant is introduced, with a pressure on a refrigerant discharge port side, where the cooling refrigerant is discharged, within the casing of the drive motor, an internal pressure on the refrigerant supply port side of the casing is exerted as one pressure on the self-operated regulating valve, and an internal pressure on the refrigerant discharge port side of the casing is exerted as other pressure on the self-operated regulating valve, whereby when a differential pressure between the two pressures exceeds a set value, the self-operated regulating valve is brought into an open state.
According to this invention, the differential pressure between the internal pressure on the refrigerant supply port side of the casing of the drive motor and the internal pressure on the refrigerant discharge port side of the casing can be autonomously adjusted to an appropriate value by a valve of a simple structure and at a low price, whereby the cooling effect of the cooling refrigerant can be fully exhibited, and rotation load on the drive motor by the cooling refrigerant can be adjusted in an appropriate range.
A seventh invention is a compression refrigerating machine having a compressor configured such that a lubricating oil is stored in a casing, and the lubricating oil is circulated by an oil pump to lubricate rotary portions, and characterized in that
the self-operated regulating valve described in the second invention is interposed midway through a pipe line leading from a condenser to the casing, an internal pressure of the casing is exerted as one pressure on the self-operated regulating valve, and an oil pressure of the lubricating oil is exerted as other pressure on the self-operated regulating valve, whereby when a differential pressure between the two pressures falls short of a set value, the self-operated regulating valve is brought into an open state.
In this invention, when the oil pump stops because of a power failure, supply of the lubricating oil by the oil pump is stopped, and the oil pressure of the oil pump, i.e., the other pressure, rapidly drops. Thus, the pressure difference from the pressure inside the casing, i.e., the one pressure, is less than the set value, opening the self-operated regulating valve. As a result, stoppage of the refrigerating machine due to the power failure results in the expansion of the liquid refrigerant in the condenser, followed by its introduction into the casing. Its pressure acts on a head tank in the casing. The pressure of the refrigerant introduced into the head tank replaces the function of the oil pump, and continues to supply the lubricating oil. Even if the supply of the lubricating oil is cut off, therefore, the lubricating oil can continue to be supplied to the rotary portions which continue rotating under an inertial force. Hence, a problem, such as seizure of the rotary portion, can be avoided.
An eighth invention is a compression refrigerating machine comprising a main refrigerant system and a lubrication system provided separately and independently, the main refrigerant system including a rotary compressor having rotary portions rotatably supported by a fluid bearing using a refrigerant liquid as a working fluid, and being configured such that a high temperature, high pressure refrigerant gas formed upon compression by the compressor is condensed by a condenser, then supplied to an evaporator for evaporation, and returned to the compressor as a refrigerant gas, and the lubrication system including a refrigerant tank for storing a refrigerant liquid, and a refrigerant pump, and being configured such that the refrigerant liquid pumped up by the refrigerant pump is fed to a bearing portion of the compressor and circulated, and characterized in that
the self-operated regulating valve described in any one of the first to third inventions is interposed midway through a pipe line as a communication between a liquid reservoir of the condenser and a pipe line forming the lubrication system, an internal pressure of the liquid reservoir is exerted as one pressure on the self-operated regulating valve, and an internal pressure of the pipe line of the lubrication system is exerted as other pressure on the self-operated regulating valve, whereby when a differential pressure between the two pressures exceeds a set value, the self-operated regulating valve is brought into an open state.
According to this invention, even if the refrigerant pump breaks down to impede circulation of the refrigerant liquid through the refrigerant system, the refrigerant liquid can be supplied from the liquid reservoir to the lubrication system via the self-operated regulating valve. Thus, a problem, such as seizure of the bearing, can be avoided. Moreover, this effect can be produced by a simple-structured, inexpensive valve.